int类型转换成String ， 不足n位 在前面补0

1.String.format("%02d", 5);-->结果：05

0代表前面要补的字符

2代表字符串长度

d表示参数为整数类型

2.秒转换成时分秒

private String secToTime(int time){
        String timeStr = null;  
        int hour = 0;  
        int minute = 0;  
        int second = 0;  
        if (time <= 0)  
            return "00:00";  
        else {  
            minute = time / 60;  
            if (minute < 60) {  
                second = time % 60;  
                timeStr = String.format("%02d", minute) + ":" + String.format("%02d", second);  
            } else {  
                hour = minute / 60;  
                if (hour > 99)  
                    return "99:59:59";  
                minute = minute % 60;  
                second = time - hour * 3600 - minute * 60;  
                timeStr = String.format("%02d", hour) + ":" + String.format("%02d", minute) + ":" + String.format("%02d", second);  
            }  
        }  
        return timeStr;  
    }